Lasers can be directional light sources. However, a laser is a coherent light source, which is not suitable for general illumination applications due to its speckle property and single wavelength characteristics. Incoherent light is usually not directional and the light output has a very large angular dispersion. There are different approaches to achieve directional incoherent light sources with directional light output. One simple way is to use a focusing lens to convert light from a point-like light source, such as an LED, into a directional light beam. So far, most of the collimated light sources on the market are achieved using this approach. However, such an approach cuts off side emission from the emitter, which dramatically lowers the light intensity of the directional light output. There are also approaches using non-imaging optics to achieve directional light output, such as parabolic mirrors, mirrors with special curvatures, etc. However, to achieve a small light output beam angle, the mirror used in these approaches is of substantial size compared to the size of the light emitter. Additionally, these approaches present mirrors surface fabrication challenges, increasing the final product cost.